Global warming has struck the Bering Sea between Alaska and Russia. A new study shows that shifting temperatures already are having an impact on one of the Earth's richest habitats, affecting everything from walruses and fish to ducks and seals.

MELISSA BLOCK, host:

This is ALL THINGS CONSIDERED from NPR News. I'm Melissa Block.

MICHELE NORRIS, host:

And I'm Michele Norris. Scientists who monitor the world's climate have been keeping close tabs on the arctic. That's where they say the first signs of a warming planet are showing up. NPR's Christopher Joyce reports that now a study of the Northern Bering Sea off the coast of Alaska has uncovered a wide range of effects from warming.

CHRISTOPHER JOYCE reporting:

The Bering Sea lies north of the Pacific between Russia and Alaska, and it's very cold. At the bottom it's actually just below freezing. But the sediments down there are rich as Kansas soil, which makes clams very happy.

Ms. JACQUELINE GREBMEIER (Ecologist, University of Tennessee): There's a lot of life down there, I mean if you were to take a box, a sand box three feet by three feet, then there would be one to 10,000 of these clams.

JOYCE: Jacqueline Grebmeier is an ecologist who confesses to love the sea bottom more than any place else. She says the clams and worms and shrimp at the bottom of the Bering are what walruses and gray whales and diving ducks thrive on. It's been that way for a long time but Grebmeier, at the University of Tennessee, says the Northern Bering Sea is changing fast.

Ms. GREBMEIER: The last four years we've had extreme ice retreat. That's related to warming Pacific water coming into the Northern Bering and through the Bering Straight. In the atmosphere, we're seeing pressure differences and the winds are coming from the south. And some warmer winds heading northward.

JOYCE: So far the warming air and water doesn't seem to have affected life at the bottom, but above it's a different story. Walruses, for example, dive from floating ice to feed on the bottom. But ice is retreating from shore driving adults farther out to sea where it's too deep to feed and it's dangerous for their young.

Ms. GREBMEIER: We saw lots of baby walruses out in open water that maybe two days before had ice over it. That leaves a young, they can't keep up with it. And this is one of the things that has been projected would occur if the ice pulled back very quickly.

JOYCE: That's bad news for the native arctic people who depend on walruses. Grebmeier says they knew things were changing in the Bering. And Grebmeier says her research has confirmed their fears.

Ms. GRIBMEYER: They have an oral record that goes back thousands of years. And compared to, what they pass along from one generation to the next, this is new. They're seeing these changes going on year after year, and having to adapt to them. And finding it hard to adapt to some of them.

JOYCE: Writing in the journal Science, Grebmeier says records in the Bering Sea don't go back far enough to know for sure if global climate change is at fault here. But ecologist Lara Hansen with the World Wildlife Fund, says the changes fit predictions of what climate change should look like in the arctic. And she says it's no easy thing for a wildlife to adapt.

Ms. LARA HANSEN(World Wildlife Fund): You have species that have to move because of their thermal limits, and then you have other species that have to catch up with that movement because they don't realize it's happening, necessarily, but they're reliant on the other species. So it means that the ecosystem starts moving as a mosaic as opposed to working as a whole body.

JOYCE: The researchers say besides big mammals like walruses and whales, commercial fish species like pollack and salmon may be next to react to a warming Bering Sea, one of the most valuable fisheries in the world. Christopher Joyce, NPR News.

NPR transcripts are created on a rush deadline by a contractor for NPR, and accuracy and availability may vary. This text may not be in its final form and may be updated or revised in the future. Please be aware that the authoritative record of NPR’s programming is the audio.